Preparation of metallic and ammonium sulphates



Oct. 3, 193 9. M, s c oN C 2,175,132

PREPARATION OF METALLIC AND AMMONIUM SULPHATES Filed Dec. 26, 1934 Patented Oct. 3, 1939 UNITED STATES PREPARATION OFMETALLIOAND- AMMONI- UM SULPHATES Marcel Scrciron, Dourclan, France Application December 26, 1934, Serial No. 759,265

In Belgium January 16;

' 9 Claims.

The invention .mainly relatesto the preparation of metallic sulphates and concerns particularly the preparation of basic copper sulphates, while giving at the same time other valuble sulphates such as ammonium sulphate.

It has been found that if a suitable metalor a metal bearing material and particularly copper or a copper bearing material is exposed to the action of a suitable compound of sulphur and oxygen, such as sulphur dioxide on the one hand in the presence of air or oxygen and on the other hand in the presence of ammonia, the metal and particularly the copper is quickly attacked and basic copper sulphates are formed, Which may be separated.

The invention thus consists in attacking a suitable metal, or a material containing it, particularly copper or a copper bearing material, on the one hand in the presence of air or oxygen and on the other hand in the presence of ammonia, by means of a suitable compound of sulphur and oxygen such as sulphur dioxide in order to convert the metal and particularly the copper into basic sulphates, and separating the basic sulphates so formed.

It has further been found that equivalent results may be obtained if the attack of the material is efiected in the presence of air or oxygen by means of a solution containingammonia and a sulphur compound or compounds suchas ammonium sulphite, b-isulphite, hyposulphite or hydrosulphite used separately or intermixed.

Consequently the invention also consists in conducting the attack of the material in the presence of air or oxygen by means of an ammonia solution of a sulphur compound or compounds, such as a solution of ammonium sulphite, bisulphite, hyposulphite or hydrosulphite separately or in their various mixtures, in order to form basic sulphates of the metal of said material, particularly the copper, and separating the basic sulphates formed.

At the same time the metal and particularly the copper is attacked and converted into basic sulphates, ammonium compounds are formed in the liquors, which, after addition of sulphur and ammonia or ammonium sulphur compounds, may be used with advantage for attacking the treated material.

The invention therefore comprises a process as set forth in the preceding paragraphs, in which the liquors from the attack of the treated material and the reactions and containing ammonium compounds, and with addition of sulphur and ammonia or ammonium-sulphur compounds if necessary, are used-again for attacking the said material.

Furthenit has been found that during the attack and the. consequent conversion of the material, particularly, the copper, ammonium sulphate forms in the liquorssimultaneously to the basic metal sulphates, and that the said ammonium sulphate may beseparated from the liquors and recovered.

- The invention further comprises a process for 10 preparing. basic. metal sulphates, particularly basic copper sulphates, with simultaneousformation of ammonium sulphate, in which this ammoniumsulphate is separated out from the liquors from the attack. and thereactions as by- 1-6 precipitation of the sulphoI-metal compounds contained therein, to recover the said ammonium sulphate.

The attacked metallicmaterial need not be pure; it may be formedalso of compounds, particularly oxides or alloys, and therefore the process .is, further characterised in that the. metallic material submitted to the attack is an impure material, or a compound,*such as an oxydised compound, or an alloy, particularly of copper.

The invention also includes the treatment of the mother liquors from the attack of the starting material .efiected in the presence of air or oxygen, by means either of an oxydised sulphur compound .or, an ammonium-sulphur compound 30 or compounds asaforesaid, by means of.a base and for examplelime, giving an anti-cryptogammic product and ammonia gas which is returned to the cycle of operations.

Other featuresof the invention will more clearly appear fromthe following description of the preparation of sulphates from copper.

According to the process copper, which maybe pure or impure, or in oxydised or allied form, is attacked, in .a. suitable state of division, as .for example inthe form of granules,.scraps, hollow shot, etc., and in presence of .air or oxygen, either bymeans of sulphur dioxide in presence of ammonia and water or by means of an ammonium solution .ofa sulphite;ibisulphite, hyposulphite or 5 hydrosulphite of ammonia or also by means of an ammonium solution of a mixture of these compounds.

Under such conditions the copper is. oxydised and passes rapidly into the solution, within, which-it may be found in the form'of sludges, of basic copper sulphates together with ammonium copper compounds and ammonium-sulphate in e. liq id P ase.

The copper seems to be dissolved inthe form of cupri-ammonium-hydrate, which through reaction on the ammonium sulphur compounds or complexes from or formed within the solution is progressively converted into basic copper sulphates.

The reactions as a whole are exothermic, the rate of attack not being lessened by the temperature increase.

When the liquor is charged with sludges of basic copper sulphates, the attack may be discontinued and the sludges drained and removed while the liquid to which sulphur and ammonia or ammonium sulphite, bisusphite, hyposulphite, etc., has been added is again used for a subseqent attack.

Alternatively the sludges of basic copper sulphates may be removed in a continuous manner, the attack liquor being on the other hand maintained at all times at a proper concentration.

The removed sludges are subjected to either of the following treatments:

To the sludges is added a sufficient quantity of sulphuric acid to neutralise the free ammonia present,the whole then being filtrated and washed out on the filter. The basic copper sulphates on the filter are dried and crushed while the liquor, after the addition of sulphur and ammonia, or ammonium sulphite, ammonium bisulphite, etc., is added to the attack liquor.

, Assuming it is desired to produce normal copper sulphates from the basic copper sulphates, the material retained on the filter after neutralisation of ammonia in the preceding operation is caused to dissolve in the quantity just necessary of sulphuric acid, the product being decanted and discharged to the crystallising vessels.

Finally when anticryptogammic products are desired, a suitable quantity of lime milk is added to the sulphate containing sludges to retain the desired copper content'in the dry product, the quantity of lime not exceeding that necessary for its combination with a part of the sulphuric acid combined to the copper and the ammonia present in the sludges, respectively.

The mixture is heated to 40-50" C. with agitation, evolved ammonia being absorbed by an aqueous sulphur dioxide solution, to form ammonium sulphite which is added to the attack liquor, while the mixture of basic copper sulphates and sulphate of lime is drained out and dried after which inert substances or adhesives, for example a dextrine containing substance may be added if desired,

As already indicatedthe liquor becomes progressively charged with ammonium sulphate.

When saturation in ammonium sulphate is reached the attack is discontinued and the liquor discharged or alternatively when the described process is operated in a cyclic manner a part of the liquor is continuously discharged, said liquor being in either case subjected to one of the following treatments.

To remove the ammonium sulphate the liquor is submitted to the action of sulphur dioxide, with the consequent precipitation in the form of copper sulphite and sulphate of substantially all of copper present. After filtration, the ammonium sulphur solution is concentrated to remove the crystallised salt. The cupriferous sulphite and sulphate retained on the filter are dissolved with ammonia and the solution is added to the attack liquor. v r

Alternatively the liquor containing the ammonium sulphate and the copper-ammonium compounds is treated by means of a milk of lime,

the evoked ammonia being mixed with sulphur dioxide to form ammonium sulphite which is returned to the process together with the formation of a body containing basic copper sulphates and calcium sulphate which when dried and crushed forms an anticrytogammic powder the composition and the nature of which are those of the product known in the trade as Bordeaux mixture.

The following examples illustrate the process.

Example I.A tower l is provided at its lower part with a false bottom 2 under which is mounted a pipe 3 provided with a cock 4 for the inlet of air or oxygen under pressure, and with an outlet valve 5 for the settled material. At its upper part the tower comprises a charging opening 6 as well as pipes I and 8 for the inlet of the reagents and the outlet of the excess of air or oxygen, Copper, which may be more or less pure or impure, is introduced in the tower in a suitably divided state (scrap, copper, hollowshot, etc.) togetherwith the attack liquid in a sufficient amount to flood the metal mass.

.Theliquid for the attack is formed with a solution containing per litre 50 grams of ammonium sulphite (NI-102803 and 10 grams of ammonia (50 cc. of a solution of 0.91 s.g.).

Through the pipe 3 under the false bottom, air or oxygen is introduced, first in a relatively large quantity and subsequently in smaller quantities the excess which flows out through one of the upper pipes 8 and carry some ammonia being mixed with sulphur dioxide in an adjacent chamber 9 to form ammonium sulphite which is retained by a spray of water and returned through ID to the reaction tower,

The copper is quickly attacked and the liquid takes first a dark green and subsequently a dark blue color; thick sludges accumulate in the lower part of the tower under the false bottom,

From time to time or in a continuous manner,

either ammonium sulphite solution or sulphur dioxide and ammonia is or are introduced through the upper valved pipes to maintain the concentrations of the attack liquor.

' When a large quantity of sludges has formed, these sludges are removed from the tower, intermittently or in a continuous manner, through the lower opening 5 therein and discharged in a settling tank ll.

When the settling operation is completed, the clear liquid is separated; its content of sulphite and ammonia are restored and it is returned through l2 to the reaction tower while the sludges are treated as already described.

When the attack liquor is saturated with ammonium sulphate, or alternatively in a continuous manner, it is discharged from the reaction tower to be submitted to one of the treatments already described.

Example II.-1000 kilos of metallic copper in a divided form (scrap copper, hollowshot, etc.) are attacked in a tower by means of 500 litres of a solution containing per litre 150 grams of ammonium sulphite and 10 grams of ammonia (molecular weight).

Air is passed through this mass at the rate of 150 cubic metres per hour The temperature raises progressively to -90 C, After three hours the attack is completed; the sludges are discharged in a tank. It is found that they contain kilos of copper in the form of basic copper sulphates with some ammonium sulphate in the liquid portion or phase. The whole is submitted to the action of a sufiicient quantity of lime 76 to displace the ammonia and after drying about 350 kilos of a powder is obtained containing 32% of copper.

It is to be understood that the concentrations of the attack liquor in ammonium sulphite and ammo-nia may be modified within comparatively large limits, and the numbers indicated are by Way of example only.

I claim:

1. A process for preparing metal sulphates, particularly basic copper sulphates, comprising attacking the metal bearing material in the presence of an oxygen containing gas, by means of a reagent containing per liter of water from 50 to 200 grams of ammonium sulphite, and about 10 grams of ammonia, separating the sludges formed, and treating said sludges to remove the sulphates therefrom.

2. In a process for preparing basic copper sulphate, the step comprising attacking a copper containing material in the presence of an oxygen containing gas and ammonia by means of an oxydised ammonium sulphur compound of reducing character and water and the operation being conducted under normal temperature and pressure, thereby dissolving the copper.

3. A process for preparing basic cop-per sulphate comprising attacking a copper containing material in the presence of an oxygen containing gas and ammonia by means of an ammonium sulphur compound of reducing character and water, in order to convert the copper into basic sulphate and separating the basic copper sulphate formed.

4. A process for preparing basic copper sulphatecomprising attacking a copper containing material in the presence of an oxygen contain- .ing gas and ammonia by means of an ammonium sulphur compound of reducing character and Water, thereby converting the copper into a basic sulphate, separating the liquid phase, adding sulphur and ammonia thereto and returning it to the reaction.

5. A process for preparing basic copper sulphate comprising attacking a copper containing material in the presence of an oxygen containing gas and ammonia, by means of an ammonium sulphur compound of reducing character and water, thereby converting the copper into basic sulphate, separating the liquid phase, adding thereto sulphur and ammonia to reform ammonium sulphur compound of reducing character, and returning the liquor thus obtained to the reaction.

6. A process for preparing basic copper sulphate comprising attacking a copper containing material in the presence of an oxygen containing gas by means of a reagent comprising an oxydised. ammonium sulphur compound of reducing character and Water and a small content of free ammonia adapted to render basic the medium of the attack, the operation being conducted under normaltemperature and pressure, thereby converting the copper into basic copper sulphate, and separating the basic copper sulphate formed.

'7. A process for preparing basic copper sulphate comprising attacking a copper containing material in the presence of an oxygen containing gas by means of a reagent comprising an ammonium sulphur compound of reducing character and water and a quantity of free ammonia adapted to render basic the medium of the attack, thereby converting the copper into basic copper sulphate, separating the liquid phase, separating ammonium sulphate from said liquid phase, after this separation restoring in the liquid phase the initial ammonium sulphur compound and ammonia content, and returning it to the reaction.

8. A process for preparing basic copper sulphate comprising attacking a copper containing material in the presence of an oxygen containing gas, by means of a reagent'of reducing character comprising water, a compound of sulphur and ammonia and a small content of free ammonia in order to convert the copper into basic sulphate, and separating the basic copper sulphate formed.

9. A process for preparing basic copper sulphate comprising attacking a copper containing material under normal pressure and in the presence of an oxygen containing gas, by means of a reagent comprising water, a compound of sulphur and ammonia of reducing character and a small content of free ammonia adapted to render basic the medium of the attack, thereby converting the copper into basic copper sulphate, and separating the basic copper sulphate formed.

MARCEL SERCIRON. 

